This application requests continuation of support for a Mental Health Clinical Research Center designed to coordinate and integrate multidisciplinary research on the genetic epidemiology of psychiatric disorders. This multidisciplinary research involves six long-term goals: (1) To describe and test alternative classification schemes for psychiatric disorders by means of follow-up and family studies, with emphasis on identifying clinical subgroups that are more simple and homogeneous in their mode of inheritance; (2) To evaluate mode of inheritance of traditional psychiatric disorders, putative clinical subtypes, and associated biosocial risk factors; (3) To evaluate the interaction of genetic and environmental risk factors; (4) to evaluate the effects of social selection, cohort effects, and temporal trends on the population distribution and dynamics; (5) to extend and develop quantitative methods for pedigree analysis; and (6) to ascertain population samples and clinical data of particular value in evaluating the inheritance of psychiatric disorders, including registers of twins, adoptees, and population isolates. To carry out these goals the MHCRC sponsors many independently funded projects whose efforts are enhanced and integrated by use of MHCRC core facilities. These core facilities include an administrative core, assessment units and registers for adults and children, a Genetic Methodology Facility, a Biostatistical Consultation Facility, a Human DNA Polymorphism Lab, and a Clinical Neurochemistry and Tissue Culture Lab. These facilities allow the MHCRC to serve as a comprehensive national and international resource for research on the genetic epidemiology of psychiatric disorders.